Currently, there is an upswing of bedbug infestations in the United States. Bed bugs seek blood meals from people and pets in their beds at night when the host (person or pet) is asleep. Bed bugs and their eggs can lie dormant for long periods of time, residing in cushions, mattresses, under baseboards, and in most crevices, nooks, and crannies. And, although they are not known to transmit disease, they are extremely hard to eradicate.
Traditionally, long-period chemical saturation of an infested area was the preferred method of eradicating the bedbug. However, some species of the pesky insects have been shown to have developed a resistance to pesticides. For other species, bedbugs can be eliminated using safe chemical treatments, fumigation and vacuuming, but these techniques typically must be repeated to get rid of the infestation because the chemicals only work on living bugs, and not the eggs.
An extermination of a bedbug outbreak must be completely thorough to be effective—if even one female bug survives; the area may become re-infested, as an adult female bedbug lays up to five eggs every day, with each egg taking only seven to 28 days to hatch. Each can lay several hundred eggs over its lifetime.
To make sure that no bedbug-hiding place is overlooked during the often tedious search and destroy missions, some people even hire bedbug-sniffing dogs.
Although experts disagree about the safest way to go about exterminating these pesky insects, the tried and true method is to use chemicals. However, more recently the Environmental Protection Agency of the United States Federal Government, banned the use of an industrial pesticide, Propoxur, which is already being used in commercial buildings, on crops and in pet collars, to fight household infestations of bedbugs and declared it unsafe for residential applications because it poses health risks for children and harms their nervous systems.
Chemical treatments, moreover, are only effective on living adolescent and adult bedbugs—the eggs survive, so effective chemical treatments require multiple visits over long periods of time, as the eggs incubate for 28-days. Thus, for practical time restraint reasons along with chemical-resistant species of bedbugs and human safety concerns, chemical treatments to eradicate bedbugs are disfavored and often ineffective.
More recently, applying heat to an enclosed, infected area has seen success in eradicating bedbugs. All forms of the bug (adult, nymph, and egg) are effectively killed if sustained temperatures of 114-degrees F are achieved for a minimum of 15 minutes. Of course, this requires that the innermost cushion on the sofa, the inner-most portion of the mattress, under base boards and in heating ducts, also reach this desired temperature for the desired time.
The current teaching in the art includes elevating the temperature of an infected enclosed area by using heat exchangers. Ambient air temperature rises as large fans move the volume of air defined by the enclosed area through the heat exchangers. Temperature probes strategically placed in the enclosed area monitor the achieved increase in air temperature and when a desired temperature is reached, a timing device monitors the duration. To provide a hot thermal mass to the heat exchanges, one teaching in the art instructs to provide large portable electric heaters to heat and move the air via fans. Yet another teaching instructs to couple a remotely located furnace to heat a large volume of glycol, which is then pumped to the enclosed area via a feed line and a return line. The current teaching instructs 400 liter/105.66 gallon tanks of glycol be heated to 210-degrees Fahrenheit. Because of the volume of fluid being moved, the current method is limited to a four-story building height. Higher buildings require booster pumps periodically spaced along the lines to move the column of liquid to the exchangers to a maximum of 20 stories.
One representative teaching of chemical-based eradicating systems known in the art includes the pest extermination system of King et al. in U.S. Pat. No. 6,199,770 issued in 2001 Apr. 13. King et al. teaches a piping system giving a plurality of nozzles positioned therealong, the nozzles are adapted for spraying a pesticide. A pumping system delivers the pesticide to the piping system. Limitations of King et al. include the harmful effect to humans of pesticides emitted during eradication and lingering effects thereafter, the cost and complexity of installing the piping system in a structure and/or enclosure, and that the system is very difficult to set up, tear down, and move to a second enclosure after the first enclosure has been eradicated.
One representative teaching of heat-based eradicating systems includes the “Method of Killing Organism and Removal of Toxins in Enclosures” as described by Hedman et al. in U.S. Pat. No. 6,327,812 issued on 2001 Dec. 11. Therein, Hedman et al. teach temperature-sensing probes installed in the enclosure to establish a baseline temperature and a real-time recorder to monitor temperatures as hot air is introduced through one or more ducts to raise the structure temperature to at least about 120-degrees F. This temperature is known to be sufficient to kill essentially all insects, bacteria, virus, dust mites, spiders, silver fish, fungi, and toxic molds. The heated air escapes through existing open doors and windows or through ducts to a filter assembly that captures the remains of the organisms. Hedman et al. claim that a typical building can be treated in six to eight hours.
More specifically, Hedman et al. instruct a system including one or more heaters that heat a gas, preferably air or nitrogen, to the predetermined temperature lethal to the organisms to be destroyed. For a more complete disinfection, the gas temperature is preferably at least about 1550 F., with optimum results generally be achieved with temperatures in the range of about 120 to 300-degrees F. A gas burning heater, such as a conventional propane heater is preferred as being particularly efficient in heating air. The heated gas from one or more heaters is directed to a blower, which directs the hot gas into enclosure through at least one ingress duct and at least one egress duct is provided to allow the gas to leave the structure. One significant limitation of Hedman et al. includes excess waste due to the requirement of heating gas to at least 1550-degrees F to heat a volume of air, and then move that volume of air to the enclosure. This wastes tremendous amount of energy and requires significant gas for heating and the equipment must be very large and cumbersome to move from location to location. Limitations of existing propane heaters include requiring overly large quantities of propane to achieve the desired temperature and they create moisture as a result of burning propane. Most large metro areas ban the use of propane burners as well. Temperature regulation is difficult at best, and oxygen depletion is also a result of burning propane. Placing workers in the oxygen depleted, heated environment is not possible without extra protective equipment.
Another example of a heat-eradicating system includes the “Apparatus for and Method of Eradicating Pests” as disclosed by Topp in U.S. Pat. No. 6,612,067 issued 2003 Sep. 2. Topp teaches an apparatus and system for disinfesting a large number of items by raising the temperatures of wood and wood products to a specified temperature for a specified period of time. The apparatus includes an insulated or non-insulated enclosure having a first end, a second external end, a second interior end, a left wall, a right, a rigid basal structure, a primary floor, a sub-floor, an interior ceiling, an interior sub-ceiling, a means for evenly heating the interior of the enclosure and a means of recirculating the air in the enclosure. One limitation of Topp is that the item being eradicated must fit inside the enclosure. While this approach works well for packed or crated, or palletized items for shipment, it is ill-suited for commercial and residential buildings.